The objectives of this proposal are to investigate the properties of the immunological system that provides antibodies which are found in secretions such as saliva, tears and colostrum. The studies will utilize a variety of biochemical and immunological techniques to find answers to the following questions: 1) What are the characteristics, in terms of structure and function, of the immunoglobulins in secretions as compared to those in serum? 2) What are the conditions of immunization required to induce antibody activity in the secretory immunoglobulins? Is local stimulation (intraoral, intraglandular) required, and/or is antibody induction a function of the nature of the antigen? 3) What are the properties of the specific antibodies induced in the secretory immunoglobulins? 4) Can the secretory immune system be stimulated to produce antibodies which will provide significant protection from diseases which affect mucosal surfaces and their related structures? 5) What is the role of the secretory immune system in viral diseases such as mumps parotitis and 6) What are the important interactions of the secretory immune system with the cellular and humoral immune systems?